A steering apparatus for an automobile, as illustrated in FIG. 17, is constructed so that rotation of the steering wheel 1 is transmitted to an input shaft 3 of a steering gear unit 2, and as this input shaft 3 turns, the input shaft 3 pushes or pulls a pair of left and right tie rods 4, which apply a steering angle to the front wheels of the automobile. In order to accomplish this, the steering wheel 1 is fastened to and supported by the rear end section of a steering shaft 5, and this steering shaft 5 is inserted in the axial direction through a cylindrical shaped steering column 6, and is supported by this steering column 6 such that it can rotate freely. The front end section of the steering shaft 5 is connected to the rear end section of an intermediate shaft 8 via a universal joint 7, and the front end section of this intermediate shaft 8 is connected to the input shaft 3 via a different universal joint 9. The intermediate shaft 8 is constructed so that the shaft can transmit torque, and can contract along its entire length due to an impact load, so that when the steering gear unit 2 is displaced in the backward direction due to a primary collision between an automobile and another automobile, that displacement is absorbed, which prevents the steering wheel 1 from displacing in the backward direction via the steering shaft 5 and hitting the body of the driver.
In order to protect the body of the driver, this kind of steering apparatus for an automobile requires construction that allows the steering wheel to displace in the forward direction while absorbing impact energy during a collision accident. In other words, after the primary collision in a collision accident, a secondary collision occurs when the body of the driver collides with the steering wheel 1. In order to protect the driver by lessening the impact applied to the body of the driver during this secondary collision, construction is known (refer to JP51-121929(U) and JP2005-219641(A)) and widely used in which an energy absorbing member, which absorbs an impact load by plastically deforming, is provided between the vehicle body and a member that supports the steering column 6 that supports the steering wheel 1 with respect to the vehicle body so that it can break away in the forward direction due to an impact load in the forward direction during a secondary collision, and displaces in the forward direction together with the steering column 6
FIG. 18 to FIG. 20 illustrate an example of this kind of steering apparatus. A housing 10, which houses the reduction gear and the like of an electric power steering apparatus, is fastened to the front end section of a steering column 6a. A steering shaft 5a is supported on the inside of the steering column 6a such that it can only rotate freely, and a steering wheel 1 (see FIG. 17) can be fastened to the portion on the rear end section of this steering shaft 5a that protrudes from the opening on the rear end of the steering column 6a. The steering column 6a and the housing 10 are supported by a bracket 11 on the vehicle side (not shown in FIG. 18 to FIG. 20, but refer to FIG. 4, for example) that is fastened to the vehicle body so that they can break away in the forward direction due to an impact load in the forward direction.
To accomplish this, a bracket 12 on the column side that is supported in the middle section of the steering column 6a and a bracket 13 on the housing side that is supported by the housing 10 are supported with respect to the vehicle body so that they both can break away in the forward direction due to an impact load in the forward direction. These brackets 12, 13 both comprise installation plate sections 14a, 14b at one to two locations, and cutout sections 15a, 15b are formed in these installation plate sections 14a, 14b so that they are open on the rear end edges. With these cutout sections 15a, 15b covered, sliding plates 16a, 16b are assembled in the portions of the brackets 12, 13 near both the left and right ends.
These sliding plates 16a, 16b are formed by bending thin metal plate such as carbon steel plate or stainless steel plate having a layer of a synthetic resin that slides easily, such as polyamide resin (nylon), polytetrafluoroethylene resin (PTFE) or the like on the surface into a U shape, having a top and bottom plate section that are connected by connecting plate section. Through holes for inserting bolts or studs are formed in portions of the top and bottom plates that are aligned with each other. With these sliding plates 16a, 16b mounted on the installation plate sections 14a, 14b, the through holes are aligned with the cutout sections 15a, 15b that are formed in these installation plate sections 14a, 14b. 
The bracket 12 on the column side and the bracket 13 on the housing side are supported by the bracket 11 on the vehicle side by screwing nuts onto bolts or studs that are inserted through the cutout sections 15a, 15b in the installation plate sections 14a, 14b and the through holes in the sliding plates 16a, 16b, and tightening the nuts. During a secondary collision, the bolts or studs come out from the cutout sections 15a, 15b together with the sliding plates 16a, 16b, which allows the steering column 6a and the housing 10 to displace in the forward direction together with the brackets 12 on the column side, the bracket 13 on the housing side and the steering wheel 1.
In the example in the figures, energy absorbing members 17 are provided between these bolts or studs and the bracket 12 on the column side. As this bracket 12 on the column side displaces in the forward direction, the energy absorbing members 17 plastically deform so as to absorb the impact energy that is transmitted to the bracket 12 on the column side by way of the steering shaft 5a and steering column 6a. 
As illustrated in FIG. 20, during a secondary collision, the bolts or studs come out from the notch sections 15a, 15a which allows the bracket 12 on the column side to displace in the forward direction from the normal state illustrated in FIG. 19, and the steering column 6a displaces in the forward direction together with this bracket 12 on the column side. When this happens, the bracket 13 on the housing side also breaks away from the vehicle body, and is allowed to displace in the forward direction. As the bracket 12 on the column side displaces in the forward direction, the energy absorbing members 17 plastically deform and absorb the impact energy that is transmitted from the driver's body to the bracket 12 on the column side by way of the steering shaft 5a and the steering column 6a, which lessens the impact applied to the body of the driver.
In the case of the construction illustrated in FIG. 18 to FIG. 20, the bracket 12 on the column side is supported by the bracket 11 on the vehicle side at two locations, on both the right and left side, so that it can break away in the forward direction during a secondary collision. From the aspect of stable displacement in the forward direction without causing the steering wheel 1 to tilt, it is important during a secondary collision, that the pair of left and right support sections be disengaged at the same time. However, tuning in order that these support sections disengage at the same time is affected not only by resistance such as the friction resistance and the shear resistance to the disengagement of these support sections, but unbalance on the left and right of the inertial mass of the portion that displaces in the forward direction together with the steering column 6a, so takes time and trouble.
In order to stabilize the breaking away of the steering column in the forward direction during a secondary collision, applying the construction disclosed in JP51-121929(U) can be somewhat effective. FIG. 21 to FIG. 23 illustrate the construction disclosed in this document. In the case of this construction, a locking hole (locking notch) 18 is formed in the center section in the width direction of a bracket 11a on the vehicle side that is fastened to and supported by the vehicle body and that does not displace in the forward direction even during a secondary collision, and this locking hole 18 is open on the edge of the front end of the bracket 11a on the vehicle side. Moreover, a bracket 12a on the column side is such that it is able to displace in the forward direction together with a steering column 6b during a secondary collision.
Furthermore, both the left and right end sections of a locking capsule 19 that is fastened to this bracket 12a on the column side are locked in the locking hole 18. In other words, locking grooves 20 that are formed on both the left and right side surfaces of the locking capsule 19 engage with the edges on the both the left and right sides of the locking notch 18. Therefore, the portions on both the left and right end sections of the locking capsule 19 that exist on the top side of the locking grooves 20 are positioned on the top side of bracket 11a on the vehicle side on both side sections of the locking hole 18. When the bracket 11a on the vehicle side and the locking capsule 19 are engaged by way of the locking grooves 20 and the edges on both sides of the locking hole 18, locking pins 22 are pressure fitted into small locking holes 21a, 21b that are formed in positions in these members 11a, 19 that are aligned with each other, joining the members 11a, 19 together. These locking pins 22 are made using a relatively soft material such as an aluminum alloy, synthetic resin or the like that will shear under an impact load that is applied during a secondary collision.
When an impact load is applied during a secondary collision from the steering column 6b to the locking capsule 19 by way of the bracket 12a on the column side, these locking pins 22 shear. The locking capsule 19 then comes out in the forward direction from the locking hole 18, which allows the steering column 6b to displace in the forward direction of the steering wheel 1 that is supported by this steering column 6b via the steering shaft.
In the case of the construction illustrated in FIG. 21 to FIG. 23, the engagement section between the locking capsule 19 that is fastened to the bracket 12a on the column side and the bracket 11a on the vehicle side is located at only one location in the center section in the width direction. Therefore, tuning for disengaging this engagement section and causing the steering wheel 1 to displace stably in the forward direction during a secondary collision becomes simple.
However, in the conventional construction, the shape of the bracket 11a on the vehicle side is special, so the construction of connecting and fastening this bracket 11a on the vehicle side to the vehicle body becomes complex, and the assembly height becomes high, therefore there is a problem in that design freedom of the steering apparatus is lost. Moreover, the number of parts increases, the work for processing parts, managing parts and assembling parts becomes troublesome, and the costs increase. Furthermore, the assembly height, for example, the distance from the center of the steering column 6b to the installation surface on the vehicle side becomes large, and there is a disadvantage in that performing design in order that the steering column 6b does not interfere with the knees of the driver becomes difficult.
In addition, in the case of the conventional construction, in order to more completely protect the driver during a secondary collision, the following improvements are desired. In other words, in the case of construction in which the bracket 12a on the column side is supported with respect to the bracket on the vehicle side in only the center section in the width direction, even a small space existing in the support section causes rocking displacement that cannot be ignored. For example, when a space exists between the top and bottom surfaces of the of the bracket 11a on the vehicle side in the portion around the locking notch 18 and the inner surfaces of the locking grooves 20 that are formed in the locking capsule 19, this space becomes the cause of rocking displacement of the bracket 12a on the column side.
Furthermore, the inner edges of the locking notch 18 that are formed on the bracket 11a on the vehicle side directly face the edges on both the left and right sides of the locking capsule 19, however, during a secondary collision, the inner edges of the locking notch 18 rub against the edges on both the left and right sides of the locking capsule causing friction, and this locking capsule 19 comes out in the forward direction from the locking notch 18. Therefore, in order to lessen the impact that is applied to the body of the driver during a secondary collision, it is necessary for the locking capsule 19 to come out smoothly in the forward direction from the locking notch 18, and so it is necessary to keep the friction acting between the inner edges of the locking notch 18 and the edges on both the left and right sides of the locking capsule 19 low.
However, in order to maintain the necessary strength and rigidity of the bracket 11a on the vehicle side, it is often formed using a ferrous metal plate such as carbon steel. Moreover, in order to sufficiently maintain the reliability and durability of the connecting section between the bracket 11a on the vehicle side and the bracket 12a on the column side, the locking capsule is also often made using a metal material such as ferrous metal like mild steel or an aluminum alloy. When these materials are both metallic materials, there is contact between metallic materials in the section where the inner edges of the locking notch 18 and the edges on both the left and right sides of the locking capsule 19 rub and friction occurs.
The friction coefficient of the section where metallic materials come in contact is relatively large, so when large contact pressure is applied to the area where there is rubbing between the inner edges of the locking notch 18 and the edges on both the left and right sides of the locking capsule 19, there is a possibility that the locking capsule 19 will not come out smoothly in the forward direction from the locking notch 18. For example, when a diagonal force is applied in the forward direction to the locking capsule during a collision accident, large contact pressure is applied at the area where there is rubbing between these surfaces. As a result, the load required for the locking capsule to come out in the forward direction from the locking notch 18 becomes large.
JP2000-6821(A) of the related literatures discloses an energy absorbing member that plastically deforms as the steering column displaces in the forward direction together with the steering wheel in order to lessen the impact applied to the body of the driver that collides with the steering wheel during a secondary collision. Moreover, JP2007-69821(A) and JP 2008-100597(A) disclose construction in which adjustment of the steering wheel position is possible, and in which in order to increase the holding force for keeping the steering wheel in the adjusted position the friction surface is increased by overlapping a plurality of friction plates. However, in construction for supporting the bracket on the column side by the bracket on the vehicle side at only one location in the center section in the width direction, technology for keeping the load required for the locking capsule that is supported by the steering column to come out in the forward direction from the locking notch that is formed in the bracket on the vehicle side low, technology that makes it possible for forward displacement of the steering wheel during a secondary collision to be performed smoothly while keeping the construction compact and low cost, and technology for reducing the number of parts and maintaining design freedom of the steering apparatus is not disclosed in these documents.
[Related Literature]
[Patent Literature]
    [Patent Literature 1] JP51-121929(U)    [Patent Literature 2] JP2005-219641(A)    [Patent Literature 3] JP10-86792(A)    [Patent Literature 4] JP2009-196562(A)    [Patent Literature 5] JP2000-6821(A)    [Patent Literature 6] JP2007-69821(A)    [Patent Literature 7] JP2008-100597(A)